The present invention relates to methods for determining the concentration of a specified elemental substance employing x-ray fluorescence techniques, and, more particularly, to methods for determining elemental concentrations of precious metals.
Ornamental gold jewelry is typically made from just a handful of gold alloys. Such gold alloys include gold as a major component, which is most often combined with other metals such as copper, zinc, silver and nickel. Gold jewelry that is composed of either solid gold or a solid gold alloy, is relatively expensive compared to other types of jewelry. Less expensive jewelry is often produced of a common alloy such as brass (or sometimes silver). This common alloy is then plated or clad with layer of gold or a layer of gold alloy. To comply with laws governing gold commerce, such jewelry must be properly marked to indicate the type and quality of the gold layer. For example, such labels can include “gold plated” or “gold electroplated” for plated objects, as well as “gold filled” for objects made of gold-clad brass or silver. In a specific example, gold-plated sterling silver is a recognized jewelry material as long as a given gold-plated sterling silver item is recognized as such.
Gold prices, especially recently, have been rising at an accelerated rate. The rise in gold prices is accompanied by a high demand for gold. Due to the high demand for gold and its accompanying high price, the jewelry market is flooded with brass and copper articles plated with thin layers of gold purporting to be gold objects, but instead are fakes. While such gold-plated articles are legitimate and permissible under trade laws when accurately identified as a plated object, significant amounts of gold-plated articles are being passed off as, or are being identified as, being made of solid gold, or a solid gold alloy. Gold-plated items can be offered for sale, for example, to a gold reseller, such as in the case of a consumer selling personal jewelry items for cash. During a purchase of a gold item (such as gold jewelry), the purchaser typically evaluates the gold to determine its worth. This is usually a very fast process that does not permit detailed analysis. It is common for gold purchasers to purchase items represented as solid gold or as a solid gold alloy, when in reality the purchased items are instead simply gold-plated metal. Purchasing gold-plated items when represented as solid gold or solid gold alloy results in a significant loss from a purchase transaction. Accordingly, there is a need for a quick and accurate method of detecting counterfeit gold.